Tank cap with inlet air purification

ABSTRACT

A tank cap for closing a filler neck of a fuel tank for a motor vehicle with a pot-shaped inner closure body, includes a lower pot body and an upper supporting flange, supporting itself on the upper edge of the filler neck and extending outward at a right angle from the pot body, and a cap body, which is placed on the closure body, whereby the tank cap can be loosened from the filler neck by turning the closure body around a rotational axis and ambient air is able to enter through at least one air inlet in the tank cap in the connection piece, circumventing a connection piece seal against a reflux seal.

RELATED APPLICATIONS

[0001] This application claims priority under the Paris Convention basedon German Utility Model Application No. 201 18 624. 1, filed Nov. 15,2001.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The invention relates to a tank cap to close a filler neck of afuel tank for a motor vehicle with a pot-shaped inner closure body. Thecap includes a lower pot body and an upper supporting flange, supportingitself on the upper edge of the filler neck and extending outward at aright angle from the pot body, and a cap body, which is placed on theclosure body. The tank cap can be loosened from the filler neck byturning the closure body around a rotational axis and ambient air isable to enter through at least one air inlet in the tank cap in theconnection piece, circumventing a connection piece seal against a refluxseal.

[0004] 2. Description of the Related Art

[0005] A tank cap is known from German Printed Patent Specification 19910 648. This tank cap features a free travel, which protected the tankcap from unintentional opening in the case of an accident that deformsthe edges of car body. The closure that is visible from the outside isformed by the cap body, which is usually manufactured out of blackplastic, but can also be composed of sheet metal or other materials. Thefiller neck of the fuel tank, on the other hand, is closed by the lowerclosure body, which is held in the surface shell of the filler neck viaa bayonet connection or a screw connection. A seal is provided between ashoulder, usually in the upper edge, and a corresponding supportingsurface of the tank cap, and this seal prevents volatile constituents ofthe fuel from escaping into the environment.

[0006] The known tank caps feature the possibility of suctioning ambientair in order to compensate for negative pressure due to the volumewithdrawn by the fuel preparation. In this regard, in the case of knowntank caps a pot-like closure body is provided, which features aspring-loaded valve in its inner hollow space, which renders the influxof ambient air possible when applying negative pressure, and withatmospheric pressure or even excess pressure, seals the tank cap,however. Excess pressure can occur in particular in cases of accidentsif the fuel tank is heated as a consequence of a vehicle fire. In thiscase, volatile and combustible gases must be prevented from exiting fromthe fuel tank at least for a certain period of time.

[0007] The disadvantage of the known tank cap, however, is that dirtparticles or drops of water are frequently suctioned along with thesuctioned ambient air. Even if a fuel filter is provided in the area ofthe further mixture, these particles are undesirable, especially sincethe fuel filter as a rule is not in a position to filter out moisturefrom the fuel.

[0008] Hence, those skilled in the art have recognized a need for a tankcap that prevents the penetration of foreign bodies as effectively aspossible without impeding the pressure compensation between the tank andthe environment. The invention fulfills these needs and others.

SUMMARY OF THE INVENTION

[0009] Briefly and in general terms, the invention relates to a tank capfor closing a fuel tank of a motor vehicle with a pot-shaped innerclosure body. The tank cap includes a lower pot body and an uppersupporting flange, supporting itself on the upper edge of the fillerneck and extending outward at a right angle from the pot body, and a capbody, which is placed on the closure body. The tank cap can be loosenedfrom the filler neck by turning the closure body around a rotationalaxis and ambient air is able to enter through at least one air inlet inthe tank cap in the connection piece, circumventing a connection pieceseal against a reflux seal. The tank cap includes at least one aircollection space for the collection and interim storage of the suctionedambient air, whereby the air inlet is formed by the front inletopenings, which connect the air collection space with the environment,and an overflow possibility, which connects the air collection spacewith the interior of the filler neck.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010]FIG. 1 shows a side view of a tank cap;

[0011]FIG. 2 shows a sectional view of the tank cap shown in FIG. 1 withsuction purification and free travel;

[0012]FIG. 3 shows a top view of the closure body of the tank cap shownin FIGS. 1 and 2;

[0013]FIG. 4 shows a three-dimensional view of the closure body shown inFIG. 3; and

[0014]FIG. 5 shows a view from below of the ratchet body of the tank capshown in FIGS. 1 through 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] A tank cap that prevents the penetration of foreign bodies aseffectively as possible without impeding the pressure compensationbetween the tank and the environment is attained by at least one aircollection space for the collection and interim storage of suctionedambient air. The air inlet is formed by front inlet openings, whichconnect the air collection space with the environment, and an overflowpossibility, which connects the air collection space with the interiorof the filler neck.

[0016] Due to the development of the tank cap in accordance with theinvention, the air can now be calmed to begin with when passing throughthe cap into the air collection space, which results in foreign bodiesand undesired gases being able to separate from the ambient air. Due tothe overflow possibility, a portion of the calmed ambient air flows intothe tank connection piece, whereby, as a result of the calming of theinfluxed air, dirt particles and gases separate so much from the calmedair that only purified air enters the filler neck. The dirt particlesremain in the collection space, while, after the negative pressuresuctioning the ambient air subsides, for instance when the motor isturned off and the supply of gasoline is interrupted, the other gasesmake their way through the inlet openings into the open air again.

[0017] In a preferred development of the tank cap, the air collectionspace is formed by an annular hollow space. This annular hollow spacesurrounds the filler neck, whereby it is preferred that the inletopenings be arranged in such a way that the ambient air can flowradially into the annular hollow space. For this purpose, severalpreferably also a plurality of inlet openings can be provideddistributed equidistant over the circumference.

[0018] With this development, the closure body preferably features asupporting flange, which can extend outward in particular at a rightangle to the rotational axis and rests with a lower surface on an edgeof the filler neck. In the case of this development, the supportingflange is connected with the cap body, for example via a snapconnection, and the inlet openings can be arranged in the transitionarea from the supporting flange to the remaining part of the closurebody.

[0019] The tank cap is constructed in such a way that in the case of anaccident a situation is avoided where the closure body is torn out ofthe filler neck. To this end, with the application of tensile force as aresult of deformations to the outer cap body, a fracture possibility isprovided, which already yields with the occurrence of such forces, whichthe screw connection or ratchet connection of the closure body with thefiller neck might still be able to tolerate.

[0020] In order to form these safety features, the supporting flange canbe provided with a groove-shaped recess on its underside or even on theupper side, which recess weakens the connection of the supporting flangewith the remaining portion of closure body thereby providing a targetfracture location. If the cap body is now connected with the outer edgeof the supporting flange, with the occurrence of greater forces, thesupporting flange will break off from the remaining part of the closurebody thereby effectively avoiding a loosening of the closure body fromthe connecting piece. In addition to the annular groove, the inletopenings contribute to the weakening of the material in this case.

[0021] Of course, instead of an annular air collection space concentricto the rotational axis, several air collection spaces can be provided,which are connected with the environment via individual inlet openings.An overflow possibility is created from the air collection space, whichoverflow possibility renders the admission of the calmed air into thefiller neck possible. This overflow possibility can be realized in avariety of ways, in the simplest case it is a leakage between the capbody and the closure body.

[0022] Normally, the cap body is an injection molded plastic part thatfeatures a hand grip projecting upward. This hand grip is manufacturedin such a way in an injection molding process that a correspondinggroove is produced for the hand grip on the underside of the cap body inthe area of the bridge-like elevation. This groove is already adequateas an overflow possibility if an annular groove is provided as an aircollection space. If, on the other hand, a plurality of air collectionspaces is provided, an overflow possibility must naturally be createdfor each of the air collection spaces. This can occur, for example, bythe underside of the cap body remaining spaced from the upper side ofthe supporting flange by using small distancing elements. The side edgesof the supporting flange should however be clamped into the cap body inthis design in such a way that direct entry of the ambient air into theconnection piece is avoided so as not to diminish the effect of calmingthe inlet air.

[0023] As is already the case with the known tank caps, the closure bodyfeatures a ratchet connection by virtue of which a force transmissionoccurs when closing the tank cap. If the torque applied by a personexceeds a specific amount, the ratchet connection slips through anddamage to the plastic parts from too deep or too vigorous screwing intothe often metallic filler neck can be avoided.

[0024] In the case of known tank caps, a spring-loaded component is usedto realize the ratchet function, which component is connected with thecap body and slides off into the hollow cylindrical closure body on aninner running surface. Now it is preferred that this ratchet connectionbe realized via a collar manufactured of flexible material, which isalso connected with the cap body. In this case, the closure body alsofeatures a pot body inserted into the filler neck, which has a runningsurface on its inner surface shell for the ratchet body embodied as aring element.

[0025] The outer surface shell of the ratchet body and the runningsurface are each provided with locking teeth, whereby the locking teethare embodied in such a way that they can slide off into one another inthe closing direction and effect an interlocking hold in oppositeopening rotational direction. To this end, two oblique planes preferablymanufactured of plastic slide off onto one another in the closingdirection, while steep locking edges engage in one another in theopening direction. By manufacturing the ratchet body and the pot bodyfrom a flexible plastic material such as polyamide, the spring can nowbe dispensed with and, along with a savings in manufacturing costs, anadditional gain in safety is achieved since a malfunction from springfracture is avoided. In addition, the assembly of the tank cap isclearly simpler due to this development.

[0026] Also in the case of the tank cap in accordance with theinvention, in addition to the possibility of the ratchet body slippingthrough, a free movement of the cap body relative to the closure bodycan be provided. This free movement is realized by a rotatableplacement, for example of the ratchet body on the cap body, if such isprovided, or of the cap body directly on the closure body, whereby afirst and a second limit stop are provided, which delimit the freetravel angle. Normally an angle of between 90° and 180° is adequate as afree travel angle since, in accordance with the invention, greaterrotations cannot occur in the case of an accident.

[0027] In addition known tank caps have the disadvantage that a freetravel angle must be realized using limit stops in the form of pins orcomparable components that can only be produced very expensively withsufficient accuracy. Moreover, there exists the danger that once the pinlengths exceed a certain extent the limit stops cannot withstand themechanical stress of the torque transmission and thus an error canoccur.

[0028] Finally, in most cases the known tank cap can be put togetherincorrectly so that a malfunction often occurs from the limit stops notbeing arranged at the planned for positions, because the closure bodywas incorrectly put together, misaligned relative to the cap body forexample. In this connection, the tank cap in accordance with theinvention can be embodied in such a way that the closure body features alower transverse support and the cap body features an upper transversesupport connected rotatably around the rotational axis of the tank capwith the lower transverse support, whereby in the lower transversesupport and/or the upper transverse support a contact surface recessedrelative to at least one raised outer area is arranged.

[0029] Malfunctions of the tank cap can be avoided in this developmentdue to the design of the lower and upper transverse supports. The twocomponents, which are preferably embodied to be bridge-like, lie on topof one another in a mounted state, whereby they penetrate each otherpartially. A recessed contact surface is arranged on one side or each onboth sides in the area of the penetration so that the two transversesupports are pivoted on top of one another, whereby the contact surfaceis delimited at least on one side by a raised outer area, which in thiscase forms the limit stop.

[0030] It is preferred that the contact surface be embodied as an evensurface, whereby it is unimportant for the function whether thisrecessed contact surface is arranged in the lower, the upper or in bothtransverse supports. As is also already the case with known tank caps,the closure body can be embodied as a hollow cylindrical pot so that, inthe case of lower and upper transverse supports that are embodied to bebridge-like, the lower transverse support is fastened with both its endsto the inner surface shell of the closure body. In this context,“fastened” means that a connection is provided between the lowertransverse support and the inner surface shell, whereby this can berealized either by an adhesive connection or a clamped joint or thecomponent can also be manufactured from one piece together with thetransverse support. The latter is offered in particular in cases wherethe lower closure body is manufactured of plastic in an injectionmolding process. In this case, the lower transverse support can be usedas a sprue channel gate, which also prevents undesired materialweakening from occurring as a consequence of solidified flow fronts inthe area of the transverse support, which has special significance forthe mechanical function of the tank cap.

[0031] The first and the second limit stop to delimit the free travelangle is formed in the case of the tank cap so embodied by the raisedouter areas of the transverse support. These raised outer areas can beprovided on both sides of the recessed contact surface, however, it isalso possible, and particularly preferred if both transverse supportsare provided with a recessed contact surface, that a raised outer areabe provided only on one side of the recessed contact surface. In thiscase, the raised area of the lower transverse support assumes thefunction of the first limit stop and the raised area of the uppertransverse support assumes the function of the second limit stop or viceversa.

[0032] The lower transverse support and the upper transverse support canbe embodied as an even bridge, whereby the form of the bridge can beselected as desired to a large extent. The raised outer areas can bedesigned in such a way that a linear or surface pressure is producedwhen applying the opposite transverse support.

[0033] The upper transverse support can be connected with the closurebody to be a single part, i.e., it can be molded in the lower side ofthe cap material. In addition to the upper transverse support, the capcan also feature a wave-like mandrel, via which the cap body isconnected rotatably with closure body. A torsion spring or even ahorizontal helical spring can be integrated into this connection therebyguaranteeing a resetting of the cap into a defined position.

[0034] The special development of the first and second limit stops viathe lower and upper transverse supports also makes it possible torealize an elastic force transmission due to an appropriate selection ofmaterial and shaping of the transverse support so that after overcomingthe free travel the operator perceives the limit stop as a harmonictransition of the force transmission. The lower and the upper transversesupports are not specified in terms of their thickness,just the flexuralstrength and the ultimate tensile strength should be sufficientlydimensioned in a direction parallel to the rotational axis.

[0035] However, since stress in this direction does not occur directly,this does not produce a particularly high requirement for dimensioning.In the rotational direction, however, the raised outer areas must beconnected with the lower cap body or with the closure body in such a waythat they can transmit the torque. The maximum torque in this connectionis prescribed as a rule by the operator's force, whereby an additionalratchet connection should be provided as a torque limitation so thatdamage can be avoided reliably.

[0036] Additional features and advantages of the invention are yieldedfrom the sub-claims and the subsequent description of a preferredexemplary embodiment on the basis of the drawings.

[0037]FIG. 1 shows a tank cap, which is formed by a closure body 1 and acap body 2 placed on the closure body 1. The cap body 2 features a handgrip 9, which the user can use to unscrew the cap body 2 along with thelower closure body 1 from the tank connection piece of a motor vehiclefor example.

[0038] In order to seal the tank connection piece, the closure body 1features a laterally projecting supporting flange 1′, which is able tosqueeze a seal between the edge of the tank connection piece and thelower side of the supporting flange 1′. To do so, the tank cap isrotated around the rotational axis D, whereby a free travel angle α isprovided in the embodiment shown, which must first be overcome by thetime the closure body 1 and the cap body 2 engage unrotatably in oneanother.

[0039]FIG. 2 shows a sectional side view of the tank cap shown inFIG. 1. Inside the closure body 1 the cap features a downward projectingpin concentric to rotational axis D, which is connected with an uppertransverse support 3 and is pivoted in the area below this in a lowertransverse support 4 of the closure body 1. The upper transverse support3 supports itself on the lower transverse support 4, whereby awithdrawal safety mechanism is provided, which prevents the upper capbody 2 from being withdrawn from the closure body 1 in the direction ofthe rotational axis D. This can be formed by a special component or evenbe realized via a plug-type connector.

[0040] It is preferred that the withdrawal safety mechanism be formed,however, by the cap body 2 extending laterally over the supportingflange 1′ of the closure body 1 and being held on this supporting flange1′ by lateral snap connections. A readjusting spring can be provided inthe area of the cap body 2, which spring is preferably arrangedhorizontally and resets the cap to a defined limit stop so that it isnot opened unintentionally in the case of an accident, but must alwaysfirst overcome the free travel angle α in the opening direction.

[0041] The lower transverse support 4 features a raised outer area 5,which is formed in the case shown by a first raised outer area 5′ and asecond raised outer area 5″. Arranged between these is the contactsurface 6 on which the upper transverse support 3 supports itself. Thiscan be seen especially well in FIGS. 3 and 5, whereby the delimitationof the free travel angle α is guaranteed by the raised outer areas 5′,5″. In this connection, FIG. 3 shows a top view of the closure body 1,while FIG. 5 shows a view from below of the ratchet body 10 insertedinto the closure body 1.

[0042] The ratchet body 10 is pivoted in a pot-like closure body 1,whereby in the lower area laterally projecting locking teeth made offlexible plastic material realize a limitation of the torsional force.In the closing direction, these teeth slip through starting at aspecific torque and damage to the closing mechanism or the seal isprecluded. These locking teeth engage in the corresponding catches ofthe closure body 1 in an interlocking manner in the opening directionand the opening torque can be transmitted in any case.

[0043]FIG. 4 shows the closure body 1 in a three-dimensionalrepresentation, whereby in this case the possibility of cleaning thesuction air can be seen particularly well. To this end, the closure body1 features a rotating groove in the upper area, which is connected viainlet openings 7 with the ambient air. From this groove the ambient aircan flow via an overflow possibility 8, formed in this case (as shown inFIG. 2) by the hollow hand grip 9, into the interior of the closure body1 and via an inlet opening arranged herein into the tank of the motorvehicle. The inlet opening is secured from gas escaping from the tank bya customary spring-loaded valve.

[0044] The inlet openings 7 are formed by bore holes distributedconcentrically over the circumference of the groove, whereby theinflowing ambient air calms down to begin with in the groove and then,after solid matter is able to separate as a result of the calming of theflow within the groove, flows via the interior of the closure body 1into the tank. The lower area of the supporting flange 1′ can beprovided with a purposeful material weakening to form a target fracturelocation thereby yielding protection from unintentional withdrawal ofthe closure body 1 from the tank connection piece in the case of theeffect of longitudinal force on the cap body 2 from an accident in thatthe supporting flange 1′ breaks off and is able to be removed togetherwith the cap body 2.

[0045] It will be apparent from the foregoing that while particularforms of the invention have been illustrated and described, variousmodifications can be made without departing from the spirit and scope ofthe invention. Accordingly, it is not intended that the invention belimited, except as by the appended claims.

What is claimed is:
 1. A tank cap to close a filler neck of a fuel tankfor a motor vehicle with a pot-shaped inner closure body, which featuresa lower pot body and an upper supporting flange, supporting itself onthe upper edge of the filler neck and extending outward at a right anglefrom the pot body, and with a cap body, which is placed on the closurebody, whereby the tank cap can be loosened from the filler neck byturning the closure body around a rotational axis and ambient air isable to enter through at least one air inlet in the tank cap in theconnection piece, circumventing a connection piece seal against a refluxseal, characterized in that: it features at least one air collectionspace for the collection and interim storage of the suctioned ambientair, whereby the air inlet is formed by the front inlet openings, whichconnect the air collection space with the environment, and an overflowpossibility, which connects the air collection space with the interiorof the filler neck.
 2. The tank cap of claim 1 characterized in that theair collection space is formed by an annular hollow space surroundingthe filler neck.
 3. The tank cap of claim 2 characterized in that theannular hollow space is arranged in the cap body and connected in termsof flow with the environment via a plurality of passage openings formingthe inlet openings.
 4. The tank cap of claim 3 characterized in that theannular hollow space is formed by a ring groove arranged in thesupporting flange, which ring groove along with the underside of the capbody that closes it at the top forms the closed hollow space.
 5. Thetank cap of claim 4 characterized in that an annular recess in the formof a groove is arranged in the support flange to form a target fracturelocation in addition to the air collection space.
 6. The tank cap ofclaim 5 characterized in that the inlet openings infiltrate the annularrecess.
 7. The tank cap of claim 6 characterized in that the overflowpossibility is formed by at least one groove-shaped overflow channel inthe underside of the cap body.
 8. The tank cap of claim 7 characterizedin that the cap body features a hollow bridge projecting outward to forma hand grip, whereby the overflow channel in the underside of the capbody is formed by the underside of the hollow bridge that is open atleast partially at the bottom.
 9. The tank cap of claim 1 characterizedin that the closure body features a ratchet body, via which it isconnected unrotatably in the opening rotational direction of the tankcap and in the opposite rotational direction rotatably with the capbody, whereby the ratchet body supports itself with locking teeth on alocking surface on the inner running surface, which featurescorresponding stop teeth in the area of the locking surface so that thelocking teeth engage in an interlocking manner in the opening rotationaldirection and slide off one another in the opposite direction.
 10. Thetank cap of claim 9 characterized in that the ratchet body is formed bya ring element, which is inserted into the body of the pot, whereby thelocking teeth are arranged on the outer surface shell of the ringelement and the ring element is connected with the cap body.
 11. Thetank cap of claim 10 characterized in that the cap body is connectedrotatably with the closure body, whereby the movement between the capbody and the closure body is delimited by a free travel angle delimiteda first limit stop and a second limit stop.
 12. The tank cap of claim 1characterized in that the closure body features a lower transversesupport and the cap body features an upper transverse support connectedrotatably around the rotational axis of the tank cap with the lowertransverse support, whereby in the lower transverse support and/or theupper transverse support a contact surface recessed relative to at leastone raised outer area is arranged.
 13. The tank cap of claim 12characterized in that characterized in that the contact surface isembodied as an even surface in the center area of the lower transversesupport and/or the upper transverse support.
 14. The tank cap of claim12 characterized in that the lower transverse support and the uppertransverse support are designed to be bridge-like, whereby the closurebody is embodied as a hollow cylindrical pot and the lower transversesupport is fastened with both its ends to the inner surface shell of theclosure body.
 15. The tank cap of claim 14 characterized in that on thelower transverse support a projecting first raised outer area isarranged on one side in the direction of the upper transverse supportand a projecting second raised outer area is arranged on the oppositeside also in the direction of the upper transverse support, whereby todelimit the free travel angle, the first limit stop is formed by thefirst raised outer area and the second limit stop is formed by thesecond raised outer area.
 16. The tank cap of claim 14 characterized inthat the lower transverse support and the upper transverse support eachfeature a contact surface, whereby the contact surface extends up to theedge on each of one of the sides of the lower transverse support and theupper transverse support, and a raised outer area extending over theplane of the contact surface is arranged on the respective other side.17. The tank cap of claim 12 characterized in that the upper transversesupport is connected with the cap body to be a single part.
 18. The tankcap of claim 12 characterized in that the lower transverse support isconnected with the closure body to be a single part.